Collapsible grinding tool



United States Patent ce 3,512,312 Patented May 19, 1970 U.S. Cl. 51-338 5 Claims ABSTRACT F THE DISCLOSURE A collapsible grinding tool having an elongated body with an elongated axial bore is provided with longitudinally extending slits for rendering the elongated body exible. Between the slits is mounted a flexible abrasive and the tool has an inoperative, collapsed position in which the ilexible abrasive assumes a bowed-in condition. A conically shaped rod is insertable into the axial bore to expand the ilexible abrasive into its operating position, which is substantially parallel to the elongated axial bore of the tool.

The present invention relates to a collapsible grinding tool having means to expand and collapse the abrasive portion of the tool.

Grinding tools of this type now known have the disadvantage of expanding at only one point so that they have a curved working surface and, the tool consequently only acts on a single point of the piece to be ground resulting in an unevenly ground place. v In order to obtain an exact grinding, it is then necessary to rigidly secure the piece to be ground. In addition, care must be taken to insure that the tool does not come out of the piece being ground in order to avoid ared inlet and outlet areas. Generally, such a flaring is dilicult to avoid and the pieces are machined with an excessive length and then shortened after grinding creating unnecessary and costly operations.

The primary object of the present invention is to provide a collapsible lgrinding tool which overcomes these inconveniences.

The collapsible grinding tool according to the present invention comprises an elongated body having an elongated axial bore and having elongated longitudinal slits for rendering the body exible, between whitch is disposed a flexible and collapsed abrasive, and means for expanding the collapsed, flexible abrasive.

The accompanying drawing represents by way of example one type of tool according to the invention.

FIG. 1 is a perspective view of the grinding tool showing same in an operative, expanded position.

FIG. 2 is a partial cross-sectional view of the grinding tool showing same in its inoperative, collapsed position.

The collapsible grinding tool of the present invention comprises a cylindrical body 1 terminating at each extremity into cylindrical portions 2 and 3 each having a diameter greater than the diameter of body 1. The end portion 3 is calibrated in such a way to prevent misuse of the tool, that is to say that the blank tool cannot penetrate in a hole which is .already tooled to .between 5 to 6 hundredths and the finishing grinding tool to between 2 to 3 hundredths.

The body 1 of the grinding tool has therein a central, longitudinally extending bore and overlying the bore are longitudinally extending slits 4 for rendering the elongated body flexible. Parallel to the bore of the tool are positioned two housings 7 and 8, formed for example by milling, and in which are mounted flexible diamond plates i and 6 constituting the abrasive parts of the tool. The body has an inoperative, collapsed position, as shown in FIG. 2, in which the exible abrasive assumes a bowed-in position and an operative, expanded position, as depicted in FIG. 1, in which the flexible abrasive assumes a straight rigid position substantially parallel to the longitudinal axis of the body. The expansion of the tool takes place by means of la conically shaped actuating rod 9 which is axially introduced in the tool.

FIG. 2 shows that the interior of the grinding tool has two cylindrical, axial bores 10 and 11 interconnected by a conical bore 12, the cone of which is dimensioned to accommodate therein the conically shaped rod 9. In this ligure, the tool has been shown in its inoperative position, in which the actuating rod 9 exerts no pressure on the ilexible body 1 of the tool. =In this position, the diamond plates 5 and 6 as well as the bottom of their respective housings 7 and 8 are slightly incurved or bowed in the direction of the bore of the tool. When it is desired to use the callapsible grinding tool, the collapsible parts of the tool are expanded and moved apart by inserting the actuating rod 9 into the longitudinally extending bore of the tool in such a way as to radially expand the bowed in liexible abrasive. The diamond plates, which are initially bowed inwardly will straighten out and become parallel to the bore of the tool as the actuating rod is driven therein. The plates, then under pressure, will continue to radially move apart in parallel fashion as the conical rod 9 is inserted further into the tool.

The use of diamond plates, in any number, has the advantage of not requiring a frequent replenishment of abrasive. In the place of diamond plates and their respective housings, it is possible to make millings in the shape of a helix or of an eagles tail, and to run in a resin, natural or synthetic, mixed with an abrasive, which need not necessarily be diamond, but can constitute a silicon or boron carbide, a corundum, or a rubicine. This latter process however requires a rectification on the edge of the metal which does not favour the cutitng or the evacuation ofthe grinding muds.

Generally, the collapsible grinding tools of the present invention have excellent durability and are especially adapted for grinding cylindrical bores without producingY an undesirable ared portion.

During use, the grinding tool having diamond plate Iabrasives requires only a small amount of lubrication or a spray of light pressure.

What is claimed is:

`1. A collapsible grinding tool comprising: an elongated body having a longitudinally extending bore therein; at least one slit in said elongated body overlying said longitudinally extending bore for rendering said elongated body exible; a flexible abrasive mounted parallel to said slit on said elongated body and having an inoperative, collapsed position wherein said flexible abrasive is bowed in towards said longitudinally extending bore; and expansible means for expanding said collapsed, llexible abrasive into an operative position wherein said llexible abrasive is substantially parallel to said elongated body and returning said flexible abrasive to its inoperative, collapsed position.

2. A tool according to claim 1; wherein said longitudi- -nally extending bore has a conically shaped portion and said expansible means comprises a conically shaped rod insertable into the conically shaped portion of said longitudinally extending bore to expand said collapsed, ilexible abrasive into its operative position.

3. A tool according to claim 1;wherein said elongated body has a plurality of housings on the periphery thereof; and said flexible abrasive comprises a plurality of flexible, abrasive plates each mounted in @ne of said housings.

4. A tool according to claim 3; wherein said plurality of flexible, abrasive plates are diamond plates.

5. A tool according ,to claim 3; Where each of said plurality of exible, abrasive plates consists of a mixture of Y resin and abrasive material.

References Cited UNITED STATES PATENTS f OTHELL M. SIMPSQN, Primary Examiner 

